幽狗尾草 you gou wei cao

Cenchrus parviflorus Poiret in Lamarck, Encycl. 6: 52. 1804; Chaetochloa geniculata (Poiret) Millspaugh & Chase; Panicum geniculatum Poiret; P. pallidefuscum Schumacher; P. rubiginosum Steudel; Setaria glauca (Linnaeus) P. Beauvois var. pallidefusca (Schumacher) T. Koyama; S. gracilis Kunth; S. pallidefusca (Schumacher) Stapf & C. E. Hubbard.

Annual or short-lived perennial with basal buds or a short knotty rhizome. Culms erect or geniculate, 20–90 cm tall. Leaf sheaths keeled, glabrous; leaf blades stiff, flat or involute, 5–30 × 0.2–0.8 cm, glabrous or adaxial surface pilose at base, apex acuminate; ligule ca. 1 mm. Panicle densely cylindrical, 2–15 × 0.5–1.2 cm; branches reduced to a single mature spikelet subtended by 8–12 bristles; axis pubescent; bristles golden or purplish brown when mature, 2–3 times spikelet length. Spikelets elliptic, 1.8–2.5 mm; lower glume ovate, 1/3 as long as spikelet, acute; upper glume broadly ovate, ca. 1/2 as long as spikelet, obtuse; lower floret neuter; lower palea firmly membranous, lanceolate, about as long as the upper floret but narrower, keels wingless, minutely papillose; upper lemma ovate-elliptic, finely rugose. Fl. and fr. Oct–Dec. 2n = 72.

Mountain slopes, roadsides, waste places. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hunan, Jiangxi, Sichuan, Taiwan, Yunnan [throughout the tropics and subtropics].

Forms with perennating basal buds persisting for more than one season are sometimes separated as a different species, but there are no other distinguishing features and this character is probably of little significance. Specimens lacking basal parts become impossible to assign to species. However, if they are separated, Setaria pallidefusca is the correct name for the annual form.

The perennial form of Setaria parviflora has been known as S. geniculata P. Beauvois, but that name was based not on Panicum geniculatum Poiret (1798), as has been widely supposed, but on P. geniculatum Willdenow (1809), which applies to a different species.

This species is a forage grass and is used medicinally.